asp net objectdatasource updating - Radiometric dating on fossils
The potassium/argon method gave an age of 72.5 plus or minus 0.2 million years ago (mya), a possible error of 0.27%; the uranium/lead method gave an age of 72.4 plus or minus 0.4 mya, a possible error of 0.55%; and the rubidium/strontium method gave an age of 72.54 plus or minus 0.18 mya, a possible error of 0.25%.
(Previous Page || Next Page) The study of the sequence of occurrence of fossils in rocks, biostratigraphy, reveals the relative time order in which organisms lived.
Although this relative time scale indicates that one layer of rock is younger or older than another, it does not pinpoint the age of a fossil or rock in years.
The decay from parent to daughter happens at a constant rate called the half-life.
The half-life of a radioactive isotope is the length of time it takes for exactly one-half of the parent atoms to decay to daughter atoms.
The isotopes of a given element have similar or very closely related chemical properties but their atomic mass differs. Its radioactive isotope potassium-40 has 19 protons and 21 neutrons in the nucleus (19 protons 21 neutrons = mass number 40).
Atoms of its stable isotopes potassium-39 and potassium-41 contain 19 protons plus 20 and 22 neutrons respectively.
Age determinations using radioactive isotopes have reached the point where they are subject to very small errors of measurement, now usually less than 1%.
For example, minerals from a volcanic ash bed in southern Saskatchewan, Canada, have been dated by three independent isotopic methods (Baadsgaard, et al., 1993).
Each kind of atom has also been assigned a mass number.Tags: Adult Dating, affair dating, sex dating